The present invention relates to a data reading mechanism for disk apparatuses, and more particularly to a data reading mechanism for faithfully reproducing data and sector servo information recorded on a magnetic recording medium a multi-zone recording (MZR) system.
In a disk apparatus according to the prior art, for instance a magnetic disk apparatus using a sector servo system, each track on the magnetic recording medium is divided into a plurality of sectors, each of which is provided with a positioning information area, into which magnetic head positioning information is written, and a data area, into which recorded data are written. In this magnetic disk apparatus, while a lower recording frequency is used for recording magnetic head positioning information than for data, a low-pass filter, adjusted to the optimal frequency characteristic for reading out the data written into the data area, and a differentiating circuit are used to reproduce the magnetic head positioning information and the data when they are to be read out of the magnetic recording medium.
However, in an MZR system, since the recording efficiency is increased by equalizing the bit recording densities on the inner and outer circumferences of the magnetic recording medium, the data recording frequency on the outer circumference of the recording medium is higher than that on the inner circumference. On the other hand, the recording frequency in the head positioning information area is constant irrespective of the position of the recording medium. As a result, in an MZR system, the recording frequency in the data area and that in the head positioning information area may greatly differ from each other.
If the recording frequency in the data area greatly differs from that in the head positioning information area, there will occur a decline in the read margin of the magnetic head positioning information reproduced by the low-pass filter and the differentiating circuit, which are adjusted to the recording frequency in the data area. As a result, in the worst case, there will arise a read error in the magnetic head position information, and the positioning of the magnetic head will be thereby made difficult.